The invention relates to a rotor of the type indicated in the preamble of patent claim 1 for a turbo machine as well as a turbo machine having a rotor. In addition, the invention relates to a method of the type indicated in the preamble of patent claim 12 for manufacturing a rotor for a turbo machine.
This type of rotor is already known from the prior art and comprises damping elements for damping blade vibrations that are introduced into through-channels or relief channels on the side of the blade neck between adjacent blades as so-called under-platform dampers. Because of their position relative to the vibrating system, these damping elements, however, frequently do not offer sufficient damping of the different forms of vibration.
EP 1 795 703 A2 discloses a bladed rotor, in which, below its respective blade platform, each rotating blade has a cooling chamber, into which the cooling air is conducted during the operation of the associated turbine. On its end facing away from the blade neck of the rotating blade, the cooling chamber is sealed by means of a damping element and there is one or more outlet openings in the blade platform, through which the cooling air can exit. Alternatively, it is provided that the cooling chamber is fluidically decoupled from the inner cooling channel of the rotating blade and is provided with cooling air by means of inlet openings in the damping element. The damping element essentially comprises a plate-shaped element, which, in the mounted state, extends linearly along a corresponding sealing surface of the cooling chamber. The radially upper end region of the damping element is supported against a lateral surface of an adjacent rotating blade. Underneath the sealing surface of the cooling chamber are formed projections that are disposed at an acute angle to the sealing surface of the cooling chamber and that support corresponding end regions of the damping element that are approximately V-shaped in cross section. Due to the acute angle between the sealing surface of the cooling chamber and the projections, friction forces are produced during the operation of the turbo machine and these forces are used for sealing the cooling chamber as well as for damping vibrations. Since the damping element not only damps vibrations, but simultaneously must seal a relatively large surface, both the damping element and the rotating blade are subject to high structural limitations.
In addition, it is known from EP 0 511 022 B1 to brace rotating blades of a rotor against one another via a wire-like damping element by guiding the damping element through the blade elements. This solution, however, in particular, has the disadvantage that the wire-like damping element is found in the flow path or annular channel. In particular, this solution is not applicable or is only conditionally applicable in the case of internally cooled blades.
It is known from EP 1 944 466 A1 to dispose damping elements in pockets of adjacent rotating blade shrouds in a rotor for a turbo machine. During a rotation of the rotor, the damping elements are moved radially upward due to centrifugal force and thus bring about a mechanical coupling of the rotating blade shrouds. This solution, however, is not suitable for rotors without an external shroud. Further, an optimal adjustment of the vibration damping is also not possible with this system.